Concrete stair mold



Oct. 12, 1943.

F. KOGL CONCRETE sTAIR MOLD Filed April 16, 1941 4 Sheets-Sheet l l A I Oct. 12, 1943. F. Kocsl.

CONCRETE STAIR MOLD Filed Apri; 1e, 1941 4 Sheets-Sheet 2 SWW/wrom /kAA/K Kon Oct. 12, 1943. F, KOGL 2,331,701

CONCRETE STAIR MOLD Filed April 16, 1941 4 sheets-'s119912 5 3 v l fil ,.mwmf

Wouw Oct. 12, 1943. F. KoGL CONCRETE STAIR MOLD med April les,V 1941 4 Sheets-Sheet 4 Patented Oct. 12', 1943 CONCRETE STAIR MOLD Frankv Kogl, St. Paul, Minn., assigner of Avfour per cent to Minnie M. Clark, South St. Paul,

Minn.

Application April 16, 1941, Serial No. 388,772

(Cl. 25a-118) 14 Claims.

This invention relates to improvements in molds for precasting concrete stair structures.

The primary object of the invention is to provide a mold in which a selected number of steps may be cast in a monolithic unit and withk side runners adapting the structure for use in lawn terraces. Another object is to provide a mold having provision for forming gutters alongside the steps and a transverse groove or channel adjacent the junction of each treaddand riser, in such manner that Water running from the steps will be conducted by said grooves toward the gut` ters to run out from the lower ends thereof. Another object is to provide a mold of this kind in which the Width and height of the treads and risers, respectively, may be readily adjusted in order to vary the length and pitch of the stair. Still another object is to provide a mold in which the side runners may be readily cut away when it is desired to use the structure within a house, as for instance for basement or apartment stairs. Still a further object is to provide an improved means for mounting the upright posts of protectective railings where such devices are desired.

These and other more detailed and specific objects will be disclosed in thecourse of the following specicaticn, reference being had to the accompanying drawings,in which- Fig. l is a perspective View of a step or stair structure particularly adapted for lawn or terrace use and having side runners and gutters.

Fig. 2 is a fragmentary'plan view of the mold as set up for forming the structure of Fig. l.

Fig. 3 is an enlarged cross section along the line 3--3 in Fig. 2, and showing the manner of supporting and disposing the railing mounting nuts in the mold.

Fig. 4 is a somewhat similar View but showing the lower portion of a railing post mounted on a fragment of a cast structure by .means of the nuts shown in Fig. 3.

Fig. 5. .is an enlarged longitudinal section through the moldshowing the `same in its inverted or casting position, and .with the mold lied with a cementitiousmaterial.

Figli is a fragmentary end View, on an enlarged scale, looking at the intended upper end of the cast stair structure inthe mold, and showing the end closures for the uppermost tread and the upper end of the side runner.

Fig. 7 is a perspective View of an end closure for theA runner.

Fig. 8is a diagrammatic sideelevation indi-` cating the manner inwhicli stair structures cast in my mold may be connected'togeth'e'r in end to end relation where agreater numberof steps may be required.

Fig. 9 is a view similar to Fig. 6, but showing end closures for the lower end of the casting and mold.

Fig. l0 is a greatly enlarged fragmentary longitudinal section through one tread and riser portion of` the mold, showing the same reverted from its position in Fig. 5, and indicating in dotted lines the manner in which the treads Vand risers may be adjusted in width and height respectively.

Fig. 11 is a substantially vertical cross section taken through one sideoi. the mold as shown in Fig. l0.

Fig. 12 is a perspective View of a stair structure cast withoutthe side runners and gutters and particularly adapted for use as a basement stair or the like.

`prior Patent No. 2,161,822, issued June 13, 1939.

Referring now more particularly, and by refe erence characters to the drawings, my mold Yin*- clud'es as its primary parts, an outer or center form A and inner form B, and side forms C, all of which are shaped and adapted to moldthe stair structure of Fig, l having the treads D, risers E, and side or runners F.

The .outer form comprises a plurality of outer tread. and riser forming members in the?Y form v of'iplate members lil, which are .bent alonglongitudinal fold lines Il, to provide the tread and riser plates I2 and i3 disposed'substantially at right angles to each other as' shown. One plate l0 thus formed, is provided for each step "and the length ofthe plates is such that they are just nicely t between the side forms C. To make the. platesl extremely rigid Iprovide' a plurality of L-shaped brace straps I4, whichV are welded .or otherwise secured to the plates'in spaced relation as clearly shown. Along` each exposed edge of the plates I9, I provide inwardly spaced guard membersor pieces yI5 of angular cross section having their ends or edges I1 turned angularly and slidably engaged with inner surfaces of the plates. The guard pieces I5 thus provide angular slide ways I9, which are adapted to receive the rigid connection angles designated at 23. The webs 2I-22 of the angles 2G are disposed substantially at right angles to each other, and when entered into the slide Ways I9, of adjacent plates II and I2 will so connect the plates that they will assume the stepped formation clearly shown. For fastening the assembled plates together, I provide stud bolts 23 which are welded or otherwise rigidly secured to the guard pieces I5 and passed outwardly through openings 24 (Fig. 10) in the angles 20 and through slots 25 in the plates I0 and straps I4. The slots 25, are elongated vertically on the risers and horizontally on the treads or in the direction of the straps I4 and, by adjusting the nuts 26 on the stud bolts 23, the plates IG may obviously be L' spread apart at their adjacent edges in order to increase the effective width of the tread plates I2, and height of the riser plates I3. This adjustment is shown in dotted lines in Fig. 10, and it will be evident therefrom that the overall length of the cast unit .of steps may thus be increased or decreased as may be required. Likewise by adjusting the effective area .of either treads or risers either alone, or in certain proportions, the pitch of the cast structure may be varied Within a considerable range.

The side forms C include the elongated at side plates 21 which are rigidly braced by outer channels 28 and which are connected by transverse tie-rods 23. In setting up the forms, the assemble plates I0, in whatever adjustment may be selected, are disposed between the side plates 21 and the nuts 30 on the ends of the tie-rods 29 are drawn tight to thereby draw the side plates 21 against the ends of the plates IQ. This fastening is made as near fluid tight as possible, and distortion of the side plates 21 is pre- Vented by the aforesaid channel 23 and other brace members 3| in order to prevent the plates from sagging away from the outer step form. The plates 21 are considerably longer than the forms in order to provide space for adjustment of the form A.

Along the lower edges of the side plates 21, I provide hat bars 32 which are disposed ilush with said edges and rigidly welded thereto and secured then to the outer surfaces of the bars 32 are the angle irons 33, which serve to mount the runner form portions of the mold but which depend below the lower edges of the bars 32 and f side plates 21 in order to form the angular channels or grooves 34 as shown in Figs. 11 and 14. The angles 20 at the junction of their webs 2l ners of the plates I0 and angles 25 are in each case rounded in order to provide a smoothly rounded contour for the step and likewise, at their extremities, the plates I2 are turned downwardly smoothly as shown at 3G in Fig. l1 in order to prevent the formation of sharp edges at the ends of the step treads.

It will further be noted that the inward spacing of the guard plates I5 will result in the formation of shallow grooves or channels 3ln .of considerable width at the junction of each tread and 22 are provided with endwise extended lugs 35 which are adapted to fit into the grooves 34 and slide freely therealong. In its casting position the mold is inverted as shown in Fig. 5, disposing theV grooves 34 uppermost and thus the lugs 35 will serve to swingably support or suspend the plates I3 and associated parts of the outer step form A between the side forms. The lugs thus permit the adjustment of the tread and riser plates as heretofore described, mean- While keeping all of the plates in proper alignment between the sides of the mold. The tie bars 29 are, of course, so located between the side plates 21 that they will not interfere with, or contact the outer form A, when such adjustments are made.

Attention is directed to the fact that the corand riser. The channels Sl1 thus formed in the risers E are of advantage in that they dene a nosing 38a along each tread in accordance with modern step construction. The channels 31a in the treads also have an advantageous function as will presently appear.

In addition to the side plates 21, the side forms C each include the trough shaped runner forms which are designated generally at 31, and which at their inner edges carry the rigidly mounted angle bars 3B adapted to be secured by means of bolts 33 with their horizontal webs in overlapping engagement with the outwardly turned webs of the aforesaid angle bars 33. The outer walls 4D of the forms 31 extend considerably above the lower edges of the side plates 21, in the casting position of the mold, While the inner wall 4i, through the overlapping bars 38 and 33 are spaced substantially away from the side plates as best seen in Fig. 11. The runner forms 31 are rigidly braced by straps 42 and at outer edges carry the angle bars 43 which are welded in place and which have outwardly turned webs 44.

The inner form B is of sectional construction comprising for each step a trough-like member G5, formed of sheet material bent to provide inner tread and riser forming portions or plates i6 and 41, respectively. At their ends, the tread plates 46 of each of the members 45 are turned upward angularly as represented at 48 in order to bring the ends of the members out to a common plane of the edges of both plates 4E and 41. The length of the members 45 is such that, in the assembled position of the mold, the angularly bent ends 48 will stand well away .from the side plates 21, as shown in Fig. ll, in order to permit the cementitious material to be lled out and around the angle bars 33 and 38, and into the runner forms 31, as will later appear.

Angle irons or cross bars 43 are Welded, or otherwise rigidly secured, to the edges of the plates 4B and 41 and these angle irons extend crosswise of the mold outwardly into overlapping relation to the bars 43 on the runner forms 31. At their ends, the angles 43 are joined by tiebars 50, welded in place at their ends 5I, and for each tiebar, I provide two set screws 52 which are threaded through the bars and may be brought to bear against the webs 44 of the angle bars 43 in the inverted casting position of the mold shown in Fig. 5. It will be evident that adjustment of the set screws 52 will permit the members 45 each to be raised and lowered toward and away from the outer form A to thus make thickness adjustments of the treads and risers of the stair structure.

It is understood, of, course, that in assembling the form, the members 45 are disposed with their respective riser plates 45 and 41, substantially parallel to, and spaced from, the corresponding outer tread and riser plates I2 and I3 to provide casting cavities for the treads and risers. To prevent displacement of the members 45 I employ C-clamps 53 which may be hooked as shown at 54 over the webs 44 of the angle bars and by adjusting the screws 55 of the C-clampsit will be evident that the tiebars 5E) may be urged toward the angle bars 43. `By locating the C- olamps between the respective pairs of set screws 52 for each tiebar, the clamps may act as` pivots so that the member's 45 may be rocked angularly about transverse axes by proper adjustment-of the set screws. The purpose of this adjustment will be described hereinafter.

In the operation of the mold, it is inverted and reverted, and to facilitatesuch operation I provide end members 56 whichnjoin theV side plates 21 and at their centerscarry endwise extended pins 51. Bails or hangers 58 may `bepivotally engaged with the pins 51 and, bythel use of -an overhead crane or lift (notshown) connectedto the bails,.the entire mold may be raised or lowered as required, and readilyv turned over about the axes of the pin with the outer form A asu sembled between the side plates 21A and locked at any desired adjustment..

The mold `is rst. inverted .as shownin Fig. 5, and the inner form members d5 put in place. It will be noted that the 'members 45, when properly installed, are spaced apart,.,as represented at 59, substantially along the junction of the treads and risers to thus provide spaces through which the cementitious material may be poured down into the cavities between inner and outer forms, and likewise the trough-.like runner forms 31 nowropen upwardly inthls position of the mold so that material can be Vpoured directly thereinto. The entire mold may thus be quickly and conveniently lled and by suitablyvibrating the forms the material may be settled into place without the formation of voids orv air bubbles.

Suitable reinforcing rods or grids 60 may be laid into the outer frormbefore the' inner form is put in place in order to provide added strength for the structure in accordance withusual practice.

The uppermost tread, or the space in which that tread is cast, must beclosed at its end in order to prevent the lescaperof materialthereat, and for this purpose I provide an end plateiil r(Figs. 5V and 6)'which` extends the lfull distance between theside plates 2 'l. For mountingv the end plate SI the angleZll inserted at the edge of the adjacenttread plate I2 has a downwardly turned web 62` against which the lower edge of the plate 'EI is mounted andsecured by means oi bolts Slots E4 in the plate 5I pass the bolts 643 and permit adjustment of the Vend plate to insure that it fully covers this open end of the mold. Closure members t5 are also provided at each end of the'plate SI and extend outwardly therefrom over the angle bars 33 and 38 and into the runner `forms 31 to provide end closures for therunners in suitable alignment with the edge of the upper tread. For mounting the closures 65, I employ bolts 56 passed through the ends voi the plates B'and through slots 61 in tie plates 61a on inner ends of the said closures, thus permitting adjustments to correspond with those of the end plate 5I itself` Attention is directed.. to the fact that the end closures 65 havev the Yangularly turned and arcuated wings 68 which enter the runner forms 31 and extend rst substantially parallel with the upper tread forming plate I2, and then curve out to meet the bottom walls 69 "of 'the Vforms 31. The result of this" shape 'and position of the wings 68 iss'h'own in the rounded upper end portion 69 of the runners Fin Fig. 1'.

At the riser plate I3 forming the lower'most that -itvwill extend substantially above the levelv of' themold in its invertedl position andA then provide a flat end plate 1D (Figs. 5 and 9),- fastened by bolts 1I- and slots 12,` to permit further extension if it may be required.- This construction, of course, cuts off the lower rise flatly and at the proper angle with respect to the lowertread as clearly shown in Fig. 1. However, I-here again provide end closures 13, mounted upon the end plate 1%, by bolts 14 and slots 15, and shaped and adapted toenter the runner .forms 31 and cut the runnersoif flush withlower riser.

Attention is directed to` the fact that, toward theirlower ends, the runners F curve outwardly to a'point substantiallyush with'the lower tread as represented at 16 in Fig.'1. The runners thus will start Afrom a point substantially flush with the sidewalk against which the lower end ofthe steps are abutted, and when properly mounted, the upper edges of the runners will be substantially level with the lawn in order to prevent any obstruction to the use of the lawnmower. Likewise of course, the upper ends of the runners will fall substantially flush with the walk leading `to the house. The installation and mounting of the steps are not shown in the drawings since it is wellknown in the art. To provide the foregoing rounded portion 16 of the runners,V the runner forms 31 increase in depth toward their lower ends and the bottom walls 69 of the forms are curved, as best indicated at 11 in Fig. 5.

With the mold in its inverted position, the exposed upper edges along the spaces 5Q,-and of course the upper open sides of therunner forms 31, may be readily smoothed off with a trowel to properly surface thel outside ofthe structure- After the material has thus been poured and smoothed olf, the mold is allowed to stand untilV the material h'ardens, veither naturally or through the application of steam for more rapid curing, and then the various end enclosures and the inner form members 45 are removed. The mold is then reverted and lowered to a support upon which the cast structure mayrest and the tie rods 29 are lloosened so that the entire mold `maybe pulled from the casting. After the mold is removed, it is of course reassembled, ready for the next operation.

The shape of the side forms C is such that a gutter G is formed between theends of the steps and the adjacent runners F by the angle bars 33 and 38 and innerwalls il of the forms 31.' These gutters G extend from end to end, yor from top to bottom, of the stairs and will lead off any water leaves or similar materials from the steps down onto the sidewalk. The recesses .or channels 3121 in each tread D, have an important function inthis respect. The water dripping from each tread to the channels therebel'ow will be conducted by the channels out to the gutters G 'and it is found that the outer tread plates I2, as they support the cernentitious mixture in the mold, havey a very slight tendency to sag and thus they will slightly crown the channels causing them to slope from the centers to the ends of the'steps to facilitate this action.

Obviously-in setting up the mold, the end 'closures for-the uppermost treadmay be appliedfat any tread plate I2 to thus out the steps off in any desired number. -In making the aforesaid height of the risers, the-inner form members 45 may be readily shifted back and forth in order to properly locate them with respect to theouter form and may of course be locked by the set screw 52 and C-clamp 53. Likewise, wherever necessary, the members 45 may be tilted or adjusted to vary the thickness and sectional shape of the treads and risers to best meet the stress requirements for steps of different sizes and lengths.

As heretofore stated, it is desirable to vibrate the mold as the material is poured, and in practice, I have found it best to apply this vibration directly to the inner form C. As an effective arrangement for this purpose I may connect the angle bars 49 with a removable channel or rigid bar 18 (Fig. 5) and upon this bar, I may mount any conventional form of vibrating device (not shown), one well known type being known to the trade by the name Syntron.

Under some circumstances, it may be desired to anchor a number of my stair structures together in end to end relation thus providing a greater number of steps than can be conveniently Yhandled and molded in one unit. To thus connect the steps, I may embed the elongated tubular members or pipes 80 in the runners F in the process of casting the straiis and permit the ends of the pipes to open at the ends of the structure as seen in Fig. 1. When adjacent step sections are then butted together they may be connected the mold by screws 82b and when removed they will provide openings 33 through which the pins may be inserted. The openings may of course be plugged after the pins are in place. Or in lieu of the foregoing, a longer length of pipe may be telescoped through the pipes 89 as will be understood. In either case the joint between step sections may be filled with a caulking compound and the connecting pipes will of course additionally serve as reinforcing means for the steps.

It is frequently desired to inount railings upon the steps, and for this purpose I provide the device shown in Figs. 2, 3, and 4. Upon the outer form or the side form, at any desired locations thereon, I mount iiat members 83, Which are welded in place and have spaced openings 84 registering with similar openings in the adjacent wall of the mold. In initial setting up the mold, suspension bolts 85 are dropped through the openings 84 and nuts 85 are screwed on the ends of the bolts in such position that they will be l supported adjacent to the inner form Wall represented at 81 in Fig. 3. During the casting operation, the bolts 85 are retained rigidly in place by tapered wedges 88 placed through loops or clips 89 on the members 83 and bearing at their ends upon the heads of the bolts. Prior to removing the casting from the form, the wedges 88 are removed and the bolts 85 unscrewed, thus leaving the nuts 86 embedded in the concrete and forining passages 80 opening upwardly through the Surface of the casting. The railing posts, as indicated at 9|, are then provided with base anges 92 having openings 93 to register with the passages 98 and mounting bolts 84 may be entered through the passages 99 and screwed into the nuts 8B to anchor the railing in place. To prevent the accumulation of water in the passages 9G, the lower ends thereof may be drilled or knocked out, as represented at 85 in Fig. 4, and the passages 90 iii.)

may if desired, be provided in all the castings and then plugged with cork or the like until their use isudesired.

The stair structure with the runner is best adapted for outdoor use of course, but it may be used indoors for basement or apartment stairs oi the like, and the sidewalls built up upon the runners. However, by removing the side forms C or, more specifically the troughiike runner forms 31, a structure of the kind shown in Fig. 12 having simply the straight lateral edges H may be cast. The mold thus arranged, is shown in Fig. 13 and it will be noted that the side plates 2l are ex tended by narrow auxiliary plates 98 which along one edge have the angle bars 8l adapted to be secured to bolts 98 to the hereinbefore described angle bars 33, thus disposing the plates 98 and 2l iiush at their inner sides. The opposite edges of tne auxiliary plates 96 also carry angle bars 99 for trie mounting and adjustment of the cross bars 49 in the manner previously described. Hooks Ib' may be embedded in the steps (Fig. 12) as an aid to mounting and supporting them.

It lnay be desirable in casting the structure ol' Fig. 12, to dispense with the adjustment or the risers l', but adjustment or' tile treads J is oi advantage particularly in that it serves as a convenient means ior varying the pitch also as shown in Figs. l0 and 12. I may employ small i'ormer or iecessing plates Hill secured beneath the outer treads and ioim recesses lul for the reception oi' non-skid, pads cr mats mi, siiown in Fig. i2.

It is understood that suitable modiiicatioiis may be made in the structure as disclosed, provided such modifications come within the spirit and scope oi` tile appended claims. Having iiow therefore 1`ully illustrated and described my invention, what I claim to be new and desire to protect by Letters Patent is:

1. A mold for precast'ing a monolithic concrete stair structure having a plurality oi" steps, the said mold including members for forming outer surfaces of the treads and risers of the steps, and separate angle members adjustably connecting the tread and riser forming members to each other at the junction of the treads and risers and adjustable to permit variations in the height oi' the risers and width of the treads, the said tread and riser forming members having slideways to receive the said angle members.

z. A mold for casting a concrete stair structure having a plurality oi' steps, including an outer forni made up oi separable sections Ioi eacli step, each of said sections having a riser iorniing portion and a tread forming portion disposed substantially at right angles to each other, angle members adiustabiy connecting the edge ci' each riser roi-nung portion to the adjacent edge oi' each tread forming portion and permitting adjustment oi the eiiective areas or' said portions, and said angle members being arranged on the inner casting suriaces ci tlie outer form.

3. A mold for casting a concrete stair structure `'having a plurality oi` steps, including an outer iol-in made up of separable sections for each step, each of said sections having a riser forming portion and a tread forming portion disposed substantially at right angles to each other, angle members adjustably connecting the edge of each riser forming portion and permitting adjustment of the eiective areas of said portions, and guard members arranged over the said angle members at inner sides thereof and slidably engaging irrner surfaces of the tread and riser forming por tions.

4. A mold for casting a monolithic series of steps having treads and risers, comprising a sectional form adapted to define and mold outer surfaces of the treads and risers, angle members adjustably connecting the form sections adjacent the junctions of the treads and risers, land guard members slidably enclosing said angle members and disposed on the inner side of the form to thereby form channels in the treads and risers.

5. A mold for casting a series of concrete steps in a monolithic unit, comprising an outer form for dening the outer surfaces of the treads and risers of the steps, side members mounted on the said outer form, an inner form comprising a separate section for each step adapted to mold the inner surfaces of the treads and risers, and means adjustably connecting the said sections to the side members and permitting the sections to be adjusted toward and away from the outer form and to be oscillated about transverse axes.

6. The combination with a form for molding a concrete stair structure and having inner and outer forms forming casting cavities, of a mounting member on the outer form having spaced openings, bolts adapted to be passed inwardly through the openings into the cavities therebetween, removable means for retaining the said bolts in position in the mounting member, the said bolts being adapted to support threaded members between the forms and to leave said threaded members embedded in the cast structure when the bolts are subsequently removed,

and the said bolts forming passages in the cast structure for the insertion of railing mounting bolts into engagement with the said threaded members.

'7. A step mold of the character described for casting a series of steps, comprising forms for molding the component treads and risers of the steps, side plates arranged alongside the ends of said forms for closing off the ends thereof, and tie rods extending between the side plates for drawing the same tightly against the ends of the forms, the said forms being slidably supported -at their ends between the side plates for adjustment when the tie rods are loosened.

8. A step mold of the character described for casting a series of steps, comprising forms for molding the component treads and risers of the steps, side plates arranged alongside the ends of said forms for closing off the ends thereof, the said side plates having longitudinally extending grooves, and lug members extending endwise y from the forms and slidably and downwardly engaging the grooves in the side plates to support the forms therebetween.

9, A mold for casting a series of steps and comprising an outer form for molding the outer surface of the treads and risers, side members arranged alongside said outer form, separate` trough-like inner forms for molding theinner surfaces of the treads and risers of each step,

cross members attached to said inner forms, and means for adjustably connecting the cross members to the side members to support said inner forms for adjustment lengthwise along the side members.

l0. A mold for casting a series of steps and comprising an outer form for molding the outer surface'of the treads and risers, side members arranged alongside said outer form, separate trough-like inner forms for molding the inner surfaces of the treads and risers of each step, said inner forms being positioned over the outer form in the casting position of the mold, and means supporting said inner forms for up and down adjustments with respect to the outer form to vary the thickness of the cast steps.

1l. A mold for casting a series of steps and comprising an outer form for molding the outer surface of the treads and risers, side members arranged alongside said outer form, separate trough-like inner forms for molding the inner surfaces of the treads and risers of each step, and means supporting said inner forms for tilting adjustments about axes extending crosswise of the mold and to permit adjustments of the inner forms with respect to said outer form.

12. A mold adapted for casting a series of steps and side.runners therefor, comprising forms arranged for molding the tread and riser surfaces of the steps, trough-like side forms arranged along the ends of the said tread and riser forms,

said tread and riser forms being adjustable lengthwise of the side forms, and end closures supported from said tread and riser forms for adjustment therewith and engaged in said side forms for forming the ends thereof.

13. In a step mold including a form having a cavity for casting said steps, said form having an opening, adapted to receive a bolt so that its threaded end extends into the casting cavity, means on the form for rigidly engaging the bolt head and supporting the bolt in such position, a threaded member adapted to be screwed on the bolt end within the casting cavity to thereby become imbedded in the step, and said bolt head engaging means being releasable for removing the bolt from the form to thereby leave a passageway through which a railing mounting bolt may be screwed into the threaded member.

14. A mold for casting a seriesof stair steps and side runners extending lengthwise of the structure along the opposite ends of the steps, comprising center forms arranged for casting the component treads and risers of the steps, side forms arranged to cast the said side runners, and channel shaped means connecting the ends of the center forms and the side forms and spacing the side forms from said ends to thereby form gutters along inner edges of the side runners. said connecting means being so -disposed that the gutters formed thereby will fall below the level of the ends of the step treads.

FRANK KOGL. 

